Carrier aggregation enhancements for new radio (NR)

Abstract

Methods and apparatus for supporting use of multiple bandwidth parts, some of which are in a dormant state from the perspective of a User Equipment device (UE) are described. In various embodiments a multi-cell grant is supported in which a UE can be, and sometimes is, granted resources corresponding of an active bandwidth part (BWP) corresponding to a cell which is active from the UE's perspective and a BWP of a dormant cell with the multi-cell grant being transmitted to the UE on the active BWP of the active cell. Various features relate to timing determination operations used to determine downlink and/or uplink timing to be used for bandwidth portions corresponding to a dormant cell. In some embodiments a UE PRACH signal transmission on a bandwidth part of a dormant cell can be triggered by a control signal sent on a bandwidth part of an active cell.

What is claimed is: 
     
         1 . A method of operating a user equipment (UE) device, the method comprising:
 receiving a control signal on an active first bandwidth part (BWP) of an active first cell, said control signal controlling the UE device to send a Physical Random Access Channel (PRACH) signal using a dormant second BWP corresponding to a dormant second cell;   receiving a first resource grant from a first base station of the active first cell granting resources for the dormant second BWP corresponding to the dormant second cell; and   using resources granted by the first resource grant to transmit or receive data in the dormant second cell.   
     
     
         2 . The method of  claim 1 ,
 wherein said first resource grant includes information identifying: i) the dormant second BWP corresponding to the dormant second cell or ii) the dormant second cell, to which the first resource grant relates; and   wherein the method further comprises:   determining, prior to using resources granted by the first resource grant to transmit or receive data in the dormant second cell, that the first resource grant includes a grant of resources for the dormant second BWP corresponding to the dormant second cell by determining that the first resource grant includes a multi-cell flag, in addition to said information identifying: i) the dormant second BWP corresponding to the dormant second cell or ii) the dormant second cell, to which the first resource grant relates, that is set to a value indicating that the grant is a multi-cell grant.   
     
     
         3 . The method of  claim 1 , further comprising:
 using resources granted by the first resource grant to transmit or receive data in the active first BWP of the active first cell.   
     
     
         4 . The method of  claim 3 , wherein said active first cell and said dormant second cell are both secondary cells used by the UE device. 
     
     
         5 . The method of  claim 3 , wherein the active first BWP and dormant second BWP are frequency adjacent BWPs. 
     
     
         6 . The method of  claim 5 , further comprising:
 determining which resources are granted in the dormant second cell based on information included in a grant message identifying granted resources in the active first cell.   
     
     
         7 . The method of  claim 1 , wherein using resources granted by the first resource grant to transmit or receive data in the dormant second cell is performed without the UE device receiving a separate resource grant on a PDCCH of the dormant second cell authorizing use of the downlink or uplink resources granted by the first resource grant. 
     
     
         8 . The method of  claim 1 , further comprising:
 transmitting said PRACH signal on the dormant second BWP in response to receiving the control signal on the active first BWP that controls the UE device to send the PRACH signal using the dormant second BWP; and   receiving on the active first BWP or dormant second BWP timing information for the dormant second cell generated based on said transmitted PRACH signal.   
     
     
         9 . The method of  claim 1 , further comprising:
 monitoring for and receiving a set of transmissions on Synchronization Signal/Physical Broadcast Channel (SS/PBCH) blocks on the dormant second BWP.   
     
     
         10 . A method of operating a user equipment (UE) device, the method comprising:
 receiving a first resource grant from a first base station of an active first cell granting resources for a dormant second bandwidth part (BWP) corresponding to a dormant second cell;   determining a timing advance to be used for transmission on the dormant second BWP based on a timing offset between the active first cell and the dormant second cell determined from downlink signals received from said active first cell and said dormant second cell and a timing advance for the active first cell, said timing advance for the active first cell being based on at least one timing advance control signal that was received from the active first cell; and   using resources granted by the first resource grant to transmit or receive data in the dormant second cell.   
     
     
         11 . The method of  claim 10 ,
 wherein the timing advance to be used for transmission on the dormant second BWP is further based on a TAG time offset to be used when computing the timing advance for the dormant second cell from the timing advance for the active first cell,   the method further comprising:
 performing a timing advance operation for the dormant second BWP using the timing advance determined based on the timing advance for the active first cell. 
   
     
     
         12 . A method of operating a user equipment (UE) device, the method comprising:
 receiving a first resource grant from a first base station of an active first cell granting resources for a dormant second bandwidth part (BWP) corresponding to a dormant second cell;   monitoring for and receiving a set of transmissions on Synchronization Signal/Physical Broadcast Channel (SS/PBCH) blocks on the dormant second BWP;   obtaining information from a SS/PBCH block received on the dormant second BWP that indicates where a CORESET of information is located in an active first BWP, said information including an inter-cell resource block offset; and   using resources granted by the first resource grant to transmit or receive data in the dormant second cell.   
     
     
         13 . A user equipment (UE) device, the UE device comprising:
 a first wireless receiver; and   a processor configured to:
 operate the UE device to receive a control signal on an active first bandwidth part (BWP) of an active first cell, said control signal controlling the UE device to send a Physical Random Access Channel (PRACH) signal using a dormant second BWP corresponding to a dormant second cell; 
 operate the UE device to receive a first resource grant from a first base station of the active first cell granting resources for the dormant second BWP corresponding to the dormant second cell; and 
 operate the UE device to use resources granted by the first resource grant to transmit or receive data in the dormant second cell. 
   
     
     
         14 . The UE device of  claim 13 ,
 wherein said first resource grant includes information identifying: i) the dormant second BWP corresponding to the dormant second cell or ii) the dormant second cell, to which the first resource grant relates; and   wherein said processor is configured to:   determine, prior to using resources granted by the first resource grant, if the first resource grant includes a multi-cell flag, in addition to said information identifying: i) the dormant second BWP corresponding to the dormant second cell or ii) the dormant second cell, to which the first resource grant relates, that is set to a value indicating that the grant is a multi-cell grant, said UE device use of resources granted by the first resource grant to transmit or receive data in the dormant second cell being based on said determining that the first resource grant includes the multi-cell flag set to said value indicating that the grant is a multi-cell grant.   
     
     
         15 . The UE device of  claim 13 ,
 wherein said processor is further configured to operate the UE device to:
 use resources granted by the first resource grant in the active first BWP of the active first cell to receive or transmit data. 
   
     
     
         16 . The UE device of  claim 13 , further comprising:
 a wireless transmitter; and   wherein said processor is further configured to:
 operate the wireless transmitter to transmit said PRACH signal on the dormant second BWP in response to receiving the control signal on the active first BWP that controls the UE to send the PRACH signal using the dormant second BWP; and 
 operate said wireless receiver to receive on the active first BWP or the dormant second BWP timing information for the dormant second cell generated based on said transmitted PRACH signal. 
   
     
     
         17 . A user equipment (UE) device, the UE device comprising:
 a first wireless receiver; and   a processor configured to:
 operate the UE device to receive a first resource grant from a first base station of an active first cell granting resources for a dormant second bandwidth part (BWP) corresponding to a dormant second cell; 
 determine a timing advance to be used for transmission on the dormant second BWP based on a timing offset between the active first cell and dormant second cell determined from downlink signals received from said active first cell and said dormant second cell and a timing advance for the active first cell, said timing advance for the active first cell being based on at least one timing advance control signal that was received from the active first cell and on a TAG time offset to be used when computing the timing advance for the dormant second cell from the timing advance for the active first cell; and 
 operate the UE device to use resources granted by the first resource grant to transmit or receive data in the dormant second cell. 
   
     
     
         18 . A non-transitory computer readable medium including computer executable instructions which when executed by a processor of a user equipment (UE) device cause the UE device to perform the steps of:
 receiving a control signal on an active first bandwidth part (BWP) of an active first cell, said control signal controlling the UE device to send a Physical Random Access Channel (PRACH) signal using a dormant second BWP corresponding to a dormant second cell;   receiving a first resource grant from a first base station of the active first cell granting resources for the dormant second BWP corresponding to the dormant second cell; and   using resources granted by the first resource grant to transmit or receive data in the dormant second cell.